Nautical charts. Nautical Charts - Download Sample Nautical Charts

Geographic map- this is a reduced, measurable and generalized image of the earth's surface on a plane, obtained according to a certain mathematical law and conveying the location, state and relationship of various phenomena of nature and society.

Nautical chart- a special map showing part or all of the World Ocean, designed to provide navigation, solve special problems and use natural resources. MK are divided into navigation, special for the Navy, auxiliary and reference.

Navigation charts according to their purpose, they are divided into four groups: general navigation, usually called marine navigation charts;

radio navigation
navigation and fishing
lake and river

Marine navigational charts (MNCs) are the main subgroup of nautical charts that ensure the safety of navigation. They reflect in detail the topography of the seabed, the nature of the coast and the entire navigational situation in the area described by this MNC. On the MNC they perform the most important task of navigation - they keep a dead reckoning of the ship's route and determine its location; LOCs are published on a scale from 1:500 to 1:5,000,000. The choice of the LOC scale is due to the distance from the shore of ship routes. It is clear that as one approaches the coast, navigation conditions generally become more complicated, the choice of courses is limited, and the number of navigational hazards increases. Therefore, on such a map, it is necessary to have more detail in the content elements (large map load), which requires a larger scale. Depending on the scale, MNCs are divided into general, travel, private and plans.
To fish in navigation programs on a PC, nautical charts must be in .

General(generalized) charts are intended for a general study of navigation conditions in a large water basin, dead reckoning of the ship's route when sailing on the high seas, preliminary laying of the route of the upcoming passage and general navigational calculations. Such maps are usually compiled on a scale from 1:5,000,000 to 1:1,000,000. The most important lighthouses, navigational hazards located at a considerable distance from the coast, floating aids to navigational fencing exposed to dangers lying far from the coast are plotted on general MNCs.

Travel maps designed to ensure navigation along the coasts at some distance from the coast, as well as to ensure the approaches of the vessel from the sea to the coast; are drawn up on a scale from 1:500,000 to 1:100,000. Lighthouses, lights and signs for coastal navigation, all navigational hazards and all floating aids to navigation are shown on the way charts.

Private cards serve to ensure navigation in the immediate vicinity of the coast, in cramped navigation conditions (narrows, passages, fairways, etc.); they are made on a scale from 1:50 OOO to 1:25 OOO. Private MNCs are more detailed travel maps. All beacons, lights and signs, including roads and ports, all navigational hazards, including small banks and stones, all floating fencing facilities are marked on them.

Plans necessary to provide entry to ports, harbors, bays, raids and for orientation when moving within these water areas. They are made on a scale from 1:25,000 to 1:500. The same elements of the maritime situation are applied to the plans as to private maps. In appearance, the plan differs from the map in that its frame is not divided into degrees and minutes, and there are no intermediate meridians and parallels. Plans are published separately, but often they are placed in the form of sidebars on free places on travel and private maps.

Radio navigation charts(RNA) are LSM with an additional load in the form of grids of isolines, designed to simplify the graphical solution of problems of determining the position of the vessel using RTS navigation. Correction values and explanations are often also applied to the RNA, which are necessary when determining the location using the RNS.
In practice, the navigator is obliged to use a map of the largest scale for a given section of the sea, lake or river.

Special cards just like MNCs, they are intended for graphical solution of navigation problems when using special technical means or when sailing in special conditions (for example, on especially high-speed ships).

Auxiliary and reference cards include maps of various contents and purposes. The composition of this group of maps, for a number of reasons, does not remain constant and changes from time to time. The most common of the auxiliary charts are grid charts for sections of the oceans and separate seas (not covered by way charts) without elements of a special maritime environment. The most important of the reference maps are maps of recommended paths, hydrometeorological elements and soils, radio beacons and radio stations, the starry sky, time zones, etc. Reference maps, united by a common content and purpose, are often reduced to one general atlas, for example, the Atlas of tidal currents, Atlas of currents for sailing in skerries, etc.

All nautical charts according to their purpose are divided into four main groups: navigational, special, reference, lake and river.

Navigational nautical charts are designed to ensure the safety of navigation. Depending on their scale, they are divided into plans, private, travel and general maps.

Plans(scale 1:1000 - 1:2 5000) serve as a guide for ship calls to ports, harbors, bays, raids, etc.

Private cards(scale 1:2 5,000 - 1:7 5,000) are designed to ensure the safety of navigation in areas that are difficult in navigation and hydrographic terms: in narrow places, in skerries, in close proximity to the coast, etc.

Travel maps(scale 1:100,000 - 1:500,000) serve to ensure navigation between ports both in visibility and out of sight of the coast and coastal landmarks. Charts of this type are the main and most common type of nautical charts.

General cards(scale 1:500,000 - 1:5,000,000) are used for a general study of the conditions of passage by the ocean or sea and, as a rule, for the preliminary laying of the ship's path.

Special cards are published to ensure the solution of problems of a navigational-applied and special nature. The most common type of them are: radio navigation, maps of radio beacons and radio stations, navigation and fishing, grid maps and blank maps.

Radio navigation charts(scale 1:750,000 - 1:3,500,000) - general maps in the Mercator projection with special grids for determining the ship's position using the latest navigation systems.

Maps of radio beacons and radio stations(scales 1: 1,000,000 - 1: 1,500,000) show the exact location of radio beacons and radio stations serving navigation, and are usually built in stereographic projection, which allows laying radio bearings in straight lines without noticeable distortion.

Navigation and fishing charts(scales 1: 500,000 and smaller) are intended for navigational support of fishing vessels; unlike conventional navigational charts, they show places dangerous for launching trawls and other bottom fishing gear.

Grid maps(scales 1:150,000 - 1:500,000) are built, as a rule, in the Mercator projection on separate latitudinal zones and are used to lay the path of the vessel on a relatively large scale; Unlike navigation maps, grid maps do not contain any elements of a cartographic image, except for a grid of meridians and parallels.

Blank cards(scales 1:500,000 - 5,000,000 and smaller) serve as the simplest geographical basis for compiling various maps and collection sheets.

Reference cards are not used directly for navigational purposes. They are auxiliary cartographic publications containing only some of the data necessary for navigators. These include: overview maps, time zone maps, and prefabricated map sheets.

Overview maps(scales 1:650,000 - 1:20,000,000) give a general idea of the navigational-hydrographical, physical-geographical and economic-geographical features of the areas depicted on them.

Time Zone Maps are small-scale blank maps of the world or individual states with boundaries and time zone numbers, along with text (legend) explaining the use of maps.

Prefabricated sheets are blank charts of oceans and seas with marked boundaries (frames) of navigational or other large-scale nautical charts. Prefabricated sheets are used to select the necessary cards and determine their numbers.

Lake and river maps designed to ensure safe navigation on lakes and navigable rivers.

Lake maps(scales 1:100,000 - 1:250,000) in their mathematical basis, content elements and symbols do not differ from marine navigational charts.

River maps(scales 1:10,000 - 1:100,000) are images of rivers with a coastal strip and coastal topography. They indicate the bottom relief, expressed by depth marks and isobaths, fairways (indicating their length in kilometers) and some other elements necessary for navigators.

The inner frame of sea and lake charts is formed by extreme meridians and parallels; Together with the intermediate ones, they form the cartographic grid of the map. The inner frame of the map is divided into degree and minute divisions: along the meridian - latitudinal, along the parallel - longitude. Thus, both side frames of the map are a linear scale and serve to measure distances on the map, as well as to measure the geographical latitude of a place. The lower and upper frames serve to take the geographical longitude of the place.

Longitudes on modern nautical charts are given from the Greenwich meridian (0°).

An atlas was created for the unified deep-water system (UGS) of the European part of the RSFSR, the maps of which were compiled in the Gaussian projection on a scale of 1:5 0 000). The depths on the maps are given relative to the normal retaining levels (NSL) in meters, and the distances along the ship's course - in kilometers from the South Port of Moscow. The signs of the situation are plotted on the maps with an accuracy that provides visual orientation.

The atlas of the unified deep-water system of the European part of the RSFSR consists of 10 volumes. Volume I of the EGS contains a diagram of the location of the Atlas volumes (a composite sheet of the Atlas volumes), then a general navigational and hydrographic review of the EGS and brief navigation conditions separately for the areas covered by each volume of the Atlas are given. In volumes II to X, at the beginning there is a combined sheet of maps of the volume and then sets of pilot maps of areas, the boundaries of which are shown on the layout of the volumes of the Atlas (in vol. I).

Depending on the purpose of the map and its scale, all elements of the content are given with varying degrees of detail, or, as they say, the map receives one or another degree of load.

When compiling charts and manuals for navigation, in addition to domestic materials, foreign manuals and manuals for navigators are widely used. The transfer of proper names and titles when using foreign materials presents significant difficulties. There can be several ways, or forms, of transferring proper names and titles.

On Soviet nautical charts, only Russian words or the words of the peoples of the USSR inhabiting the given region are used to convey proper names and names for regions of the territory of the Soviet Union.

For foreign areas, four main forms of transferring names and titles apply:

Traditional Russian;

Transferable (semantic);

Transcription (phonetic);

Transliteration (transfer of proper names and titles by replacing foreign letters with the corresponding letters of the Russian alphabet).

On nautical charts, those objects are mainly depicted and those inscriptions are made that are essential for the purposes of navigation.

When compiling marine navigation charts, special attention is paid to the image of the coast, the topography of the seabed and objects of navigational significance.

On marine navigational charts, the bottom relief represents the main characteristic of the marine situation and is the most important element of their content.

The relief of the seabed is depicted on the map in such detail that the navigator has the opportunity to accurately find out about the depths; Dangerous depths for swimming are highlighted so that they are visible at a glance on the map.

Depths on Soviet maritime navigation charts for domestic waters are indicated by numbers in meters and decimeters: depths from 0 to 5 m with an accuracy of 0.1 m; from 5 to 20 m - up to 0.2; from 20 to 50 m - up to 0.5; more than 50 ppm about 1.0.

Depths on each sea chart are reduced to a single level - zero depths. On seas where there are no tides, the average level is taken as zero depth; in tidal seas, zero depth is taken to be the lowest water level in the area, called the theoretical zero depth.

If the depths are not reduced to a single depth zero, then the charts indicate that they are expressed in meters.

For greater clarity of the image of the bottom relief, on maps, in addition to depth marks, as mentioned above, isobaths (lines of equal depths) are applied. They are usually carried out through places with depths of 10, 20, 50, 100 and 200 m, and in deep water areas - sometimes at 500, 1000 and 2000 m.

The 10-meter isobath should be considered warning for vessels with small draft and 20-meter - for vessels with large draft. Reliable isobaths are shown by solid lines, and insufficiently provided with soundings - by a dotted line. With a sharp fluctuation in depths and an abundance of cans, the so-called warning isobath, or line of danger, which limits the coastal part of the sea with shallow depths or any shallow water.

All navigational hazards on marine navigational charts are depicted with the greatest completeness. When the position of the navigational danger is established approximately, then the inscription “PS” is made on the map - “the situation is doubtful”, but if there is doubt about the existence of the danger, then it is put on the map with the inscription “SS” - “the existence is doubtful”.

The underwater relief and depths in the areas of fairways and recommended courses are shown more carefully and are necessarily indicated by isobaths.

The relief of the land is depicted only within a narrow strip visible from the sea. Rivers, roads, communication routes are shown schematically and only on approaches to the shore.

Characteristic coastline protrusions used as navigational landmarks are depicted more carefully and distinctly on maps. The shores are depicted with a characteristic in terms of height, structure and constituent rocks, which facilitates their identification. The islands are depicted in great detail, and their characteristic outlines are transmitted strictly on the scale of the map.

In the free places allotted for land, contour sketches of coasts and prominent points are also placed on the map for better orientation when sailing near the coast. The objects depicted on the map, especially those related to navigation, must have explanatory inscriptions (name, height, bearing, distance, etc.). Various notes, warnings, plans of ports, drawings of lighthouses, information about tides and tidal currents are placed in free places on the map.

From coastal aids to navigation equipment, the following are applied to maritime navigation charts: beacons and signs, radio beacons, direction-finding, radar, radio ranging and other stations, leading cables, etc.; from floating warning signs - ordinary buoys, buoys with radar reflectors, milestones, as well as floating beacons.

Aids to Navigation (Aids to Navigation) are shown in varying detail according to the purpose of the map and depending on the navigation characteristics of the area.

Only the main beacons and lights, reception or warning, are applied to the general maps, which are important at the transitions between ports and on the approaches to roadsteads and ports. Of the floating lighthouses, only those located on the high seas and "receiving" from the sea, that is, standing at the entrance to the roadstead or to the port, are applied. If there are alignments on the approach to the port, only the first (outer) alignment is shown. Illuminated buoys and daytime floating fencing are applied only at external sea hazards and on the first fairway approaching the port or roadstead.

On the travel maps, the navigational coastal and floating fencing outside the raids and ports is applied completely inside the raid - with a large detente.

All lighthouses, signs and all other navigational coastal and floating signs of the fence are applied to plans and private charts.

As navigational landmarks on sea charts, various kinds of natural objects noticeable from the sea are distinguished - mountain peaks, characteristic rocks, cliffs, river mouths, etc., as well as various kinds of noticeable structures on the coast, for example, detached buildings, factory chimneys, towers , churches, various towers.

Data on magnetic declination and magnetic anomalies are plotted on nautical charts indicating the magnitude of the declination given to a particular year and its annual change. These data are given in the title of the map, as well as with a special sign or in the form of an inscription in various places on the map at intervals of 20-30 cm.

Areas of known magnetic anomalies are outlined with a thick line; inside the contour, the inscription "Magnetic anomaly" is made and the approximate value of the anomalous declination is shown.

Information about tides and currents is given in tables, and currents, in addition, are indicated by arrows in the corresponding places on the map; The current velocities in this case are given above the arrows by inscriptions with an accuracy of 1/4 knot.

Areas that are dangerous or prohibited for navigation, areas of landfills, etc. are applied to all navigation charts. The boundaries of these areas on the maps are highlighted with conventional signs, and data on the navigation regime near them, when necessary, is given in the form of a warning on the margins of the map.

State borders and demarcation lines on maritime navigational charts are shown with the possible geographical accuracy.

Reading nautical charts

The main load of the cards is made with conventional symbols, therefore, in order to read the map, one must be able to decipher the meanings of these symbols and the abbreviated inscriptions that supplement them.

A practical guide for reading modern Soviet nautical charts and sailing guides are the books “Navigational and hydrographic terminology. Symbols and abbreviations”, “Symbols for nautical charts and plans”, sheets of symbols for pilot publications and maps of reservoirs of the Ministry of the River Fleet.

Reading the card begins with its title.

The title of the card is placed inside the frame of the card, usually on a free land field. The statutory sign is applied on top, and under it - the name of the map, i.e. the name of the area covered by the map; the numerical scale and the main parallel to which it refers are indicated; the measures in which the depths are expressed and to what level they are reduced; measures in which the heights of mountains are given; declination year and its annual change.

Then they read the inscriptions under the lower frame of the map, which indicate the year the map was compiled, the materials on the basis of which it was compiled, data on major and minor corrections.

The most common conventional signs navigators should know by heart. These include designations: signs protecting dangers and obstacles, signs of coastal landmarks, as well as those intended to determine the position of the vessel, abbreviations for the characteristics of beacons and lights, situational and warning signs, depths, alignments, fairways and recommended courses, places prohibited for navigation and setting anchored, currents.

For better contrast and readability of the maps, some of the symbols are printed in different colors.

The following points of conventional signs correspond to the location of objects on the ground:

1) for signs with an asymmetrical pattern or signs with a wide base - the middle of the base;

2) for signs of regular geometric shape - the geometric center of the figure;

3) for signs with a right angle at the base - the top of the right angle;

4) for signs formed by a combination of several figures, the center of the lower figure.

The location of the depth is the intersection of the diagonals of the rectangle enclosing the number of whole meters in the mark of the given depth.

Soils are designated by conditional abbreviations. For example: GLI - clay silt; IP - silty sand; R - shell; PI - sandy silt, etc.

The color and characteristics of the soil are given by the following abbreviated inscriptions, for example: blmp - white fine sand; srI - gray viscous silt, etc.

Own names placed on maps are most often written in full. Nomenclature terms and data characterizing the object are written in abbreviated form.

Lighthouse inscriptions can serve as an example of abbreviated inscriptions. For example, “GrPr (3) (15 s) 15MT (S) S. Art. RM k" means: "Group-flashing, three flashes per second, period 15 seconds, visibility range 15 miles, fog signal - siren, signal station, radio beacon."

The name of the lighthouse is placed next to, but separate from, the characteristic. In abbreviated form, inscriptions characterizing the features of the coastal relief and other information are also given.

Before using any navigational chart, it is necessary first of all to determine the degree of its suitability for the upcoming navigation. To do this, you need the title of the card. determine its name (the area of \u200b\u200bthe ocean, sea, bay, lake depicted on it), the numerical scale and the main parallel. According to the numerical scale of the map, it is necessary to identify the maximum accuracy of its scale and familiarize yourself with the linear dimensions of the latitude divisions on the inner side frame of the map. Then, in the heading, they read information about the zero depths and the system of measures that express them. The lack of data on the depth zero obliges one to be critical of the reliability of the depths shown on it. You should also carefully read all warnings and notes, which are a text supplement to the map, which provide information about the navigation situation in the area covered by this map, and sometimes messages about the error in the position of individual objects on it. After that, attention is drawn to the inscriptions of the map outside the frame, by which one can judge its accuracy, reliability and modernity. At the same time, attention should be paid to the year of surveying and measuring work, on the basis of which the map was compiled, to the year of publication and major proofreading, etc. If the survey was carried out a very long time ago, therefore, survey work was carried out with less accuracy due to imperfection of at this time shooting techniques and tools. Therefore, such cards cannot be sufficiently reliable. In addition, over a long period of time, changes in fairways, the appearance of shoals, bank erosion, etc., could occur in the area.

If the depths are shown on the map with large gaps, this shows that the sounding was not detailed, and therefore dangers are possible in these places. In general, all white places on the map should be looked at not as deep places, but as places where depths have not been measured. If there are no isobaths on the map, this shows that the sounding was not detailed enough to make them; such cards are less trustworthy. Locations where depths on the map are less than the depths of the rest of the area should be avoided, since it is not known how detailed the depths of these places have been surveyed. When further reading the map, it is necessary, according to the conventions adopted in cartography, to pay attention to the location of coastal and floating signs, the characteristics of the lights, their visibility range, the nature of the soil, the places of anchorages and shelters.

In all cases, it should be a rule to always use the largest scale map in the area, corrected according to the most recent data (as indicated by the date of the correction).

A map is a reduced image on a plane of part or all of the earth's surface.

Nautical charts are one of the most important tools for ensuring the safe navigation of ships. Separate sections of the sea are applied to marine navigation charts, indicating the depths and soils, the outlines of the coastline and relief, navigational signs and dangers.

The importance of nautical charts in navigation is very great. Being a reduced image of areas of the earth's surface on a plane, the nautical chart, as it were, tells the navigator about the areas and conditions in which the vessel navigates. The nautical chart warns the sailor about. dangers and at the same time tells him how best to chart his course.

Nautical charts are the oldest among geographic charts. The first known prototype of modern maps was the periods that appeared in ancient times (from the Greek "periplus" - detour, circumnavigation). The periplus contained data on the distances between coastal settlements, coastal dangers, places of shelter ...

Later, portolans (maps) appeared, which were essentially plans; drew them on parchment. With the further development of navigation and navigation techniques, portolans are being replaced by real maps with a grid of meridians and parallels plotted on them; they were not handwritten, but printed.

In 1569, the Dutch cartographer Gerard Kremer, also known by the Latin name Mercator, proposed new mathematically based principles for constructing maps, in particular, several map projections, of which the cylindrical conformal map projection is the most famous. This projection, called the Mercator projection, has become widespread, and from then to the present, nautical and other charts are compiled in this projection, requiring accurate representation of angles. The production of Russian nautical charts, organized on a state basis, was started by Peter I. Maps for the Azov and Black Seas, an atlas of maps for the Don River, thirty maps for the Gulf of Finland and a map of the Caspian Sea were compiled and published.

So, in 1714, an atlas of sea charts was published in Russian under the heading "A Book of Dimensional Degree Charts of the Ostsee or Varangian Sea", to which three private maps of the entrances to the skerries from the sea near Tverminne, Barazund and Gangut were attached. This atlas, serving the Russian fleet in the era of Peter I, was reprinted twice (in 1720 and 1723).

Cartographic work was greatly developed during the years of Soviet power. In 1953, the Marine Atlas was published - the result of many years of work by Soviet hydrographers.

In 1966, a complete set of Soviet manuals for navigation in the World Ocean was created, and in 1975, the creation of a world collection of marine navigation charts was completed, which is not inferior to the best foreign collections.

In the post-war period, expeditions on specially designed and appropriately equipped ships were regularly organized to study the hydrographic and meteorological regimes of all oceans. In 1974, the first volume of the Atlas of the Oceans, a unique scientific work on the World Ocean, was published.

The concept of loxodrome and orthodrome. If a ship sails between two points and moves in a constant course, then it will cross all the meridians and iodine at the same angle and its path will be depicted by a curved line, which is called a loxodrome (translated from Greek means "oblique run"). Loxodrome on the surface of the Earth is depicted as a spiral (Fig. 37), which approaches the pole, but never reaches it. The navigation of the vessel along the loxodrome is very convenient, since it is carried out on the same course and simplifies calculations for the entire time of the passage. However, roxodrome sailing is not the shortest distance between two crossing points.

Figure 37. Image of loxodrome and orthodrome on the surface of the Earth.

The shortest distance between two points A and B on the earth's surface (see Fig. 37) is a great circle arc passing through these two points and called the orthodrome (translated from Greek as "straight run"). The orthodrome crosses the meridians at different angles. When swimming for short distances, the difference in length between the loxodrome and orthodrome is insignificant and therefore it is neglected, since swimming along the loxodrome is more convenient. However, during long ocean crossings, navigation is carried out along the great circle, that is, along the arc of a great circle.

Building a map in the Mercator projection. The method of conditional representation of the Earth's surface on a plane is called a map projection.

Since the surface of the Earth has the shape of a ball, its image on a plane cannot be carried out without distortion. This means that there is no such cartographic projection that would not distort the earth's surface depicted on it. From a large number of different map projections, however, one can choose one that would satisfy the basic requirements for a nautical chart.

1. It is desirable that the loxodrome line (constant heading) be depicted on the sea chart as a straight line, as the simplest, laying

Rice. 38. Building a Mercator projection

Which is carried out using a ruler and a protractor.

2. All angles on the map must correspond to the same angles on the ground, and then the shape of the outlines of the land and various objects on the earth's surface will correspond to their images on the map. This means that the map projection must be conformal.

Thus, the angles measured by the navigator between any landmarks on the ground will correspond to the angles between the same landmarks on the map that meets the last condition. The visual perception of the navigation area will correspond to its image on the map. The conformal normal cylindrical Mercator projection satisfies these requirements most fully. The projection allows you to depict geographic meridians as straight lines and parallel to each other, perpendicular to another system of straight lines parallel to each other, which are geographical parallels. In order to get the Mercator projection (Fig. 38, a), let's imagine the globe, or, more simply, a geographical globe with lines of meridians and parallels plotted on it; which is "wrapped" in a cylinder along the equator, the axis of which coincides with the axis of the globe (globe). Then we will project the images of the earth's meridians and parallels onto the surface of the cylinder and expand it into a plane. The cartographic grid obtained on the plane, being a normal cylindrical projection, will look like a system of straight lines parallel to each other - earth meridians, perpendicular to other straight lines parallel to each other - parallels.

However, in this case, the length of the meridians will not change, while the parallels will stretch along the length of the equator, remaining parallel to it. The parallels near the equator will stretch slightly, but as they move away from it, that is, with increasing latitude, the stretch will increase.

Let us determine how each parallel has increased at any latitude φ. Let us denote by r the radius of the parallel AB (Fig. 38, b) and by R the radius of the Earth. The BOQ angle will determine the chosen latitude. It can be said that the length of any parallel, multiplied by the secant of the latitude of this parallel, will be equal to the length of the equator, or, extending to the circumference of the equator, any parallel is stretched in proportion to the secant of the latitude.

However, the resulting projection is not conformal, since the parallels on it stretched in proportion to the secant of latitude, and the length of the meridians remained the same. In order for it to become equiangular, it is necessary to stretch the meridians in the same way as the parallels stretched, that is, in proportion to the secant of latitude. Now the resulting projection is conformal, i.e., the similarity of figures and the equality of angles between certain directions is preserved; a line of constant course (loxodrome) will only be a straight line crossing the meridians at the same angle; the scale within the map changes slightly. Consequently, both the first and second requirements for the projection of the sea chart were met.

Scales and classification of nautical charts by purpose. The scale of the map is the ratio of the length of a line on the map to the actual length of the same line on the earth's surface. Scales are either numerical or linear. The scale, expressed as a fraction, the numerator of which is one, and the denominator is a number showing how many units of length on the surface of the Earth is equal to a unit of length on the map, is called numerical, or numerical. For example, 1:100,000 means that one unit of length on the map corresponds to 100,000 of the same units on the earth's surface (1 cm on the map, for example, is equal to 100,000 cm on the ground.

The scale showing how many larger units of length on the ground are contained in one smaller unit of length on the map is called linear. For example, 10 km in 1 cm or 3 miles in 1 cm.

On nautical charts in the Mercator projection, the linear scale is depicted by divisions of the side frames of the chart. Since the meridians in the Mercator projection stretch with increasing latitude, the length of the image on such a map of one minute of latitude, or one nautical mile, will increase with distance from the equator. When measuring distances on a map, use the side frame of the map on the same parallel as the measured distance.

Nautical charts are used to maintain navigation laying and to obtain information about the area of navigation. Cards are classified according to their purpose. All sea charts are divided into two groups: navigational and auxiliary (reference).

According to their content and scale, marine navigation charts are divided into general, route, private and plans.

General charts depict bays, seas, oceans or parts thereof. These charts are used for a general study of the conditions of navigation throughout the voyage, they perform a preliminary laying of the transition and make general calculations related to the voyage of the ship. The scale of general maps is usually from 1:500,000 to 1:5,000,000.

On the way charts depict the individual areas of the passage of the vessel, they contain all the necessary details for safe navigation and approach to the shore. Therefore, the scale of travel maps should not be too small. Travel maps are published in scales from 1:100,000 to 1:500,000.

On the way charts, the path of the vessel is laid and its places are determined. Since the way charts depict separate parts of the sea, as the ship moves, it is necessary to move from one map to another. On travel maps, depending on the areas of the sea, a certain part of the coastal strip is also depicted.

Private charts are designed for navigation near the coast and in cramped areas - straits, skerries, approaches to ports, etc. Private map scales from 1:25,000 to 1:75,000.

The plans will contain images with all the details of bays, harbours, roadsteads, ports and are intended for entering ports, passing through narrow places. Plans are drawn up on a scale from 1:500 to 1:25,000.

Geographical elements are images of the shores of the oceans, seas, bays, settlements, the topography of the seabed and land.

Navigational elements - ports, aids to navigation, sea channels, fairways, navigational hazards, navigational landmarks and other information of a navigational nature.

Inscriptions - titles of maps, various explanations and warnings, geographical names, information about the publication of the map and its corrections.

Elements of additional characteristics are small large-scale plans of ports or maps of navigationally important sections of the coast, which are placed on free places on the map sheet, as well as tables with information about tides and currents, drawings of lighthouses, etc.

All of the listed elements of the map content are applied with conventional signs and symbols, as well as conventional abbreviations, which are given in the periodically republished book "Conventional signs for sea charts and charts of inland waterways" (Appendix 2, sheets 1, 2, 3).

Before using a sea chart, you should study it carefully. To do this, you need to learn how to read a map. In order to be able to read a map, it is necessary to understand all the symbols and the abbreviated inscriptions that supplement them.

When studying a map, one should first of all begin by reading its title, all the notes and warnings placed on the map. Then you need to familiarize yourself with the navigation and geographical data of the area shown on the map; depths, soils, navigational hazards, coastlines, various navigational signs, beacons, lights. Particular attention should be paid to the study of hazards (reefs, cans sunk at a shallow depth of ships) and their navigational fencing.

Navigation charts according to their purpose, they are divided into four groups: general navigation, usually called marine navigation charts;

radio navigation
navigation and fishing
lake and river

The method of conditional representation of the Earth's surface on a plane is called a cartographic projection, and the resulting image of the meridians and parallels is called a cartographic grid. There are several types of map projections. All of them are divided into two groups - depending on the nature of the distortions and depending on the method of constructing the cartographic grid.CUT$

According to the nature of the distortions, the projections are divided into conformal, equal-area, equidistant and arbitrary projections.

On maps in a conformal projection, infinitesimal figures are depicted by similar corresponding figures on the earth's surface. The similarity of the figures makes it possible to maintain the equality of angles. On maps in an equal area projection, the proportionality of areas to the corresponding areas on the earth's surface is preserved, but the similarity of figures is not preserved. Equidistant maps maintain a constant scale in one of the main directions. Arbitrary projections do not preserve either the equality of angles or the proportionality of areas, but they have their own special properties.

According to the type of meridians and parallels of the normal cartographic grid, the projections are divided into: conical, cylindrical and azimuthal. With conical projections, the earth's surface is projected onto the side surface of a tangent or secant cone, followed by a development of this surface into a plane. With cylindrical projections, the earth's surface is projected onto the side surface of a tangent or secant cylinder. With azimuth projections, the earth's surface is projected onto a plane tangent to the earth's surface at any point.

A flat reduced image of the earth's surface, on which distortions are subject to a certain mathematical law, is called sea chart.

Flat images of small areas of the earth's surface, on which distortions can be neglected, are called plans.

The main feature that distinguishes a map from a plan is that the scale of the map is not constant, but on the plan the scale remains constant over its entire surface.

The Mercator mile is taken as a unit of a linear scale for measuring distances and differences in latitudes on a Mercator map. The length of one minute of the meridian arc on a given parallel of the map in the Mercator projection, expressed in millimeters, is called the Mercator mile.

Since the meridians on the Mercator map are stretched proportionally at each point, the image of one minute of the meridian arc changes with latitude and continuously increases as you move away from the equator. Therefore, when measuring distance on a sea chart, it is necessary to take a mercator mile on the side frame of the chart at the same latitude where the measured distance is located.

Areas close to the Earth's poles are depicted on the Mercator projection with very large distortions, and the poles themselves are not projected onto the side surface of the cylinder. Therefore, Mercator charts are compiled for latitudes not exceeding 85°.

The degree of reduction of the actual sizes of figures or lines of the earth's surface transferred to the map is called the scale. The scale is characterized by the ratio of the length of a line on the map to the length of the same line on the surface of the Earth. There are numerical and linear scales.

The numerical scale is a fraction, the numerator of which is one, and the denominator is a number showing how many units of length on the ground are contained in a unit of length on the map.

A linear scale is a graphic representation of a numerical scale and shows how many larger units of distance on the ground are contained in one smaller unit on the map.

As mentioned above, the scale is kept constant only on plans. On nautical charts, the scale is a variable and is divided into major and minor.

The main scale is the scale indicated on the map itself in its title and preserved only along certain specific directions. So, for a sea chart in the Mercator projection, the scale remains constant along the parallels and changes when moving from one parallel to another. The parallel along which the main scale indicated in the map title is observed is called the main parallel.

With increasing latitude, the scale on the Mercator projection increases, and vice versa, with decreasing latitude it becomes smaller. At all points on the map, the scale values turn out to be larger or smaller than the main scale and therefore are called private.

The scale of the map determines the accuracy with which linear measurements can be performed on it. The ultimate scale accuracy is the linear distance on the ground, corresponding to 0.2 mm on the map (the maximum distance visible to the naked human eye on paper).

how to use the sea map

Before use sea chart it needs to be studied carefully. First of all, you need to read the title of the map, notes and warnings, the year of publication and the dates of corrections. The title of the map indicates its name, that is, the area, and below the name the following data is given: the scale and the main parallel to which it is assigned; the year to which the magnetic declination is given; measures in which depths are expressed.

Depths on sea charts are reduced to a single level - zero depths. On Soviet maps in seas with tides, the lowest possible sea level is taken as zero depth, that is, the level is the lowest of the small spring waters, and for seas without tides - the average long-term level.

Depths on sea charts for domestic waters are indicated in meters as follows: up to 5 m with an accuracy of 0.1 m; from 5 to 20 m with an accuracy of 0.2 m; from 20 to 50 m with an accuracy of 1 m.

The smallest depth is the shallowest depth on the bank, reef, bar and other bottom elevations, as well as on the fairway, in the channel.

Maintained depth - the smallest depth in the channel or on the fairway, which is maintained during the entire navigation.

Distinctive depth - a depth that differs upward or downward from the surrounding depths (by at least 10% for even and 20% for uneven bottom topography).

For greater clarity, the images of the relief of the seabed on maps, in addition to depths, are plotted with isobaths (lines of equal depths). They are carried out through depths of 10, 20, 50, 100, 200 m, and in deep water areas - sometimes through depths of 500, 1000 and 2000 m.

Soils on the maps are abbreviated, for example: I-silt, Gbk-sponge, Gl-clay, Cor-corals, P-sand, R-shell, Gr-gravel, K-stone, etc. The color and nature of the soil are indicated in abbreviated form in lowercase letters, for example: zlichi - green impure silt, blmp - white fine sand, plGl - dense clay.

Elevation marks, heights of islands, above-water rocks and stones are given in meters from the sea level adopted on the maps of the given area for reading heights. Heights, mixed relative to their position, and the heights of structures are enclosed in brackets.

Navigational dangers and their protection on the maps are indicated by conventional signs. If the position of the danger is not precisely established, then conditional abbreviations are placed near it - PS (position is doubtful) or SS (existence is doubtful).

Aids to navigation for determining the ship's position are also indicated by conventional signs; and those that do not have a sign are indicated on the map by a circle with a dot in the center and an explanatory abbreviated inscription. For example: RPS - direction-finding station, pam - monument, RLO - radar landmark.

Lights of illuminating aids to navigation equipment on maps at a scale of 1:500,000 and larger are shown according to their actual color. White, yellow and orange lights are shown with orange paint; the abbreviation "g" is placed before the character of the yellow and orange lights.

The radii of circles and arcs indicating the color of the lights do not correspond to the visibility range of the light. The visibility range of fire is given in nautical miles.

On nautical charts at a scale smaller than 1:500,000, all lights of luminous aids to navigation, regardless of the type (circular or sectoral) and the color of the light, are depicted as purple "horns".

On nautical charts at a scale of 1:500,000 intended for use as general charts (inland or marginal seas), all lights, regardless of type and color, are depicted as purple "horns". The color of the fire is indicated by abbreviations before the nature of the fire.

Direct and reverse directions (true azimuths) are indicated on the alignments; the first direction is given from the coast, the second from the sea. With a dense load of the map, one direction from the coast can be indicated on the alignments. The undercarriage of navigation lines is shown as a continuous line, while the undercarriage is shown as a dotted line.

If due to the small scale nautical charts two leading lighting signs are not expressed separately and are shown at one point, then the characteristic of the fire of the front sign is given first, and then the rear.

Buoys on nautical charts are depicted in accordance with their type. No shape is shown for buoys whose shape is unknown or does not conform to the IALA Buoyage System.

At buoys, milestones and signs, top figures are shown and their color is indicated by the accepted abbreviations. In the area of the IALA Barrier System, on maps with a dense load, the markings for floating aids to navigation and non-illuminated signs may have their coloring omitted if they have top figures.

Due to the fact that in the areas of operation of the IALA Fence System, radar reflectors are installed on all floating aids to navigation, displayed in places important in relation to navigation, radar reflectors on floating aids to navigation equipment are usually not shown on maps.

On charts of inland waterways, the colors of buoys, buoys and shore markers correspond to their actual color, with the exception of white, which is given in orange.

At lighthouses and luminous signs, the characteristics of lights and other explanations are given by conditional abbreviations. For example: GrPr (4) 20s 22MT (n) ARMkROT, that is, a group flashing fire with four flashes and a period of 20 seconds, a visibility range of 22 miles, a fog signal, an autophone, an airborne radio beacon, a fog detector radio station.

Current on nautical charts are shown by arrows: the current velocity with an accuracy of 0.25 knots is written above the arrow. Information about tidal currents is placed in tables on free places on the map.

Magnetic declination for a given area is indicated on nautical charts with an accuracy of 0˚.1. The annual change in declination to the Epoch to which it belongs is placed in the title of the chart. The region of the magnetic anomaly is shown as a contour surrounded by a solid black line.

classification of nautical charts

All nautical charts are divided into navigation, reference and auxiliary maps. Navigational charts are designed to solve various navigational problems and are a mandatory official document. Navigation charts are divided into general and special.

Depending on the scale, general navigation charts are divided into general, travel, private maps and plans.

General cards are drawn up on a scale of 1:500000 - 1:5000000 and serve to maintain the dead reckoning of the ship's route when sailing on the high seas, preliminary laying and general navigational calculations.

Travel maps designed to ensure navigation near the coast and at some distance from it. Such maps are compiled on a scale from 1:100,000 to 1:500,000 along the main parallel.

Private cards designed to provide navigation when sailing in close proximity to the coast and in cramped navigation conditions, they are drawn up on a scale from 1:75000 to 1:25000.

Plans are intended to provide entry to ports, harbors, bays, raids, anchorages and for navigation within their water area. Plans are drawn up on a scale of 1:1000 - 1:25000.

Special navigation charts differ from general navigation charts in that they have an additional load for solving individual navigational and other tasks. Special navigation charts include: radio navigation charts designed to determine the position of the vessel using the RNS; navigation and fishing charts with detailed soil characteristics of the seabed, etc.

Reference and auxiliary maps different in content and purpose. Usually auxiliary charts are a cartographic grid without special elements of the sea situation. These include grid charts, blank charts, charts for calculating navigation along an arc of a greater circle, etc. Reference charts are intended for studying physical-geographical and other elements of the navigation area that cannot be shown on navigational charts. Reference maps include maps of radio beacons and radio stations, maps of recommended routes, maps of hydrometeorological elements, maps of the elements of terrestrial magnetism, collated sheets, atlases (physical and geographical data, tidal currents, surface currents, waves, wind, etc.).